Control device of non-stage transmission

ABSTRACT

A control device of non-stage transmission for vehicles comprising a V-belt and pulleys, and which serves as an electronic control unit by receiving engine control information and drive control information to generate a duty control signal according to a referece pressure of hydraulic control of the non-stage transmission, and electrically controlling transmission gear ratio in a form of electronic control device, whereby accuracy and life of the control device as well as fuel consumption and driving performance of vehicle is improved.

FIELD OF THE INVENTION

The present invention relates to a control device of a non-stagetransmission for vehicles comprising a V belt and pulleys.

BACKGROUND ART

FIG. 1 illustrates a known control device of a non-stage transmissionaccording to a prior art. This known control device was disclosed inJapanese Laid-Open Patent Publication (unexamined) No. 55-65755.

In FIG. 1, numeral 1 indicates an input shaft; numerals 2, 3 indicatepulleys of the input shaft (primary pulleys); numeral 5 indicates acylinder having a cylinder chamber 4; numeral 6 indicates a pipe line;numeral 7 indicates an output shaft; numerals 8, 9 indicate pulleys ofthe output shaft (secondary pulleys); 10 indicates a cylinder; 11indicates a piston; 12 indicates a cylinder chamber; 13 indicates a pipeline; 14 indicates a belt; 15 indicates a pump serving as a hydraulicpower source; 16 indicates a tank; 17 indicates a transmission gearratio detecting shaft; 18 indicates a sensor shoe; 19 indicates afilter; 20 indicates a transmission control valve; 21 indicates a pilotsleeve, 22 indicates a pitot pressure space; 23 indicates an annulargroove; 24 indicates an opening; 25 indicates a Pitot tube; 26 indicatesa pipe line; 27 indicates a spring; 28 indicates an actuating member; 29indicates a spring; 31 indicates a throttle cam; 32 indicates a pivot;and 33 indicates a cam follower. Numeral 40 indicates a secondaryhydraulic control valve; 41, 42 indicates sleeves; 43 indicates a space;44, 45 indicate pipe lines; 46 indicates a pitot pressure space; 47indicates a spring; 50 indicates a pivot; 51 indicates a lever; 61indicates a pivot; and 62 indicates a turning member.

In the conventional control device of above construction, the primaryoil pressure is controlled in accordance with a required transmissionpattern from the throttle cam 31 and an engine speed given from thePitot tube 25 by way of the input shaft 1. On the other hand, thesecondary cylinder oil pressure is controlled by detecting atransmission gear ratio by the transmission gear ratio detecting shaft17, and the secondary oil pressure is reduced with the transmission gearratio. Then, the pilot sleeve 21 moves to change pipe line according tothe primary and secondary oil pressures, whereby the input shaft pulley3 and the output shaft pulley 9 move to change the transmission gearratio to non-stage.

FIG. 2 (a) is a diagram illustrating a relation between cylinderpressure, i.e., engine speed ne and the primary cylinder pressure P₁ andsecondary cylinder pressure P₂. FIG. 2 (b) is a diagram illustrating arelation between transmission characteristic, i.e., engine speeddeviation Δne and transmission gear ratio R. FIG. 2 (c) is a diagramillustrating a relation between engine characteristic, i.e., enginespeed ne and engine torque τe.

In the above conventional device, however, it was not easy to achievesuch a driving performance as allowing improvement in fuel combustionand feeling in accordance with the transmission pattern supplied fromthe throttle cam 31. Change of driving performance according to type ofvehicle was not easy, either. It was impossible to accurately detectengine speed because the Pitot tube 25, serving as an engine speeddetector, was mechanically arranged. Accuracy of the transmission gearratio detecting mechanism was not achieved due to life or secularchange. It was impossible to separately control each cylinder oilpressure P₁, P₂. It was also impossible to control the cylinder oilpressures P₁, P₂ according to the intensity of engine torque.

The present invention was made to solve the above problems and has anobject of providing a control device of a non-stage transmission inwhich driving performance can be improved without deviation due to lifeor secular change, and the primary and secondary cylinder oil pressurescan be separately controlled.

DISCLOSURE OF THE INVENTION

The control device of a non-stage transmission according to the presentinvention comprises an electronic control device which receives enginecontrol information and drive control information and generates dutycontrol information, reference pressure generating means which receivesthe duty control information and generates a reference pressure forhydraulic control of cylinders of the transmission, and hydrauliccontrol means which carries out hydraulic control of the cylinders inaccordance with the reference pressure and a feedback pressure from thecylinders.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a construction of the controldevice of a non-stage transmission according to the prior art:

FIG. 2 (a) to (c) are characteristic diagrams of the device according tothe prior art;

FIG. 3 is a schematic view illustrating the control device of anon-stage transmission according to the present invention;

FIG. 4 is a schematic diagram of the electronic control unit used in thecontrol device of a non-stage transmission according to the invention;

FIG. 5 (a), (b) are respectively characteristic diagrams of the controldevice of a non-stage transmission according to the invention; and

FIG. 6 (a) to (d) are flowcharts of the electronic control unitillustrated in FIG. 4.

BEST MODE OF CARRYING OUT THE INVENTION

Referring now to the accompanying drawings, the present invention ishereinafter described in detail. FIG. 3 is a schematic view illustratingthe control device of a non-stage transmission according to the presentinvention, while FIG. 4 is a schematic diagram of the electronic controlunit used in the control device of a non-stage transmission according tothe invention.

In FIG. 3, numeral 70 indicates a pressureregulating valve comprising ascrew 71, spring 72 and sleeve 73; numeral 74 indicates a pipe line;numerals 75, 76 indicate orifices; numeral 80 indicates a primary dutyvalve comprising a coil 81, a sleeve 82 and a nozzle 83; numeral 90indicates a primary pressure control valve comprising a sleeve 91, areference pressure space 92, a feedback pressure space 93 and a spring94; numeral 100 indicates a secondary duty valve comprising a coil 101,a sleeve 102 and a nozzle 103; numeral 110 indicates a secondarypressure control valve comprising a sleeve 111, a reference pressurespace 112, a feedback pressure space 113 and a spring 114; numeral 120indicates an accelerator opening sensor; numeral 121 indicates athrottle opening sensor; numeral 122 indicates an input shaft sensor;numeral 123 indicates an output shaft sensor; numeral 130 indicates apowder clutch; numeral 140 indicates a vehicle; and numeral 200indicates an electronic control unit.

In FIG. 4 illustrating a schematic view of the electronic control unit200, numeral 201 indicates a waveform rectifier circuit; numeral 202indicates an A/D conversion circuit; numeral 203 indicates an inputinterface circuit; numeral 204 indicates a duty valve driving circuit;numeral 205 indicates a powder clutch control circuit; and numeral 206indicates a microcomputer.

FIG. 5 (a) is a diagram showing a relation between a duty D and anoutput pressure PD, and FIG. 5 (b) is a diagram showing a relationbetween a clutch current Ic and a clutch torque c.

FIG. 6 is a flowchart of the microcomputer 206, in which Figure (a)shows a main loop, FIG. 6 (b) shows an interruption program formeasuring period with interruption pulse from the sensor, FIG. 6 (c)shows an interruption program for duty control which is generated everyinversion of duty signal in order to generte a duty control signal, andFIG. 6 (d) shows an interruption program for time control which carriesout processing of time variable parameter at a certain interval.

In the control valve of above arrangement, the duty valves 80, 100generate reference pressures, each for the control valve 90 and thecontrol valve 110, in accordance with a duty signal (pulse widthmodulation signal) from the control unit 200. More specifically, whenturned ON, the hydraulic circuit is closed, and oil pressure of the pipeline 74 becomes equal to oil pressures (output oil pressures) of thereference pressure spaces 92, 112. On the other hand, when turned OFF,the hydraulic circuit is open, and the output oil pressures are reduced.The control valves 90, 110 operate to keep the output pressures constantsince oil pressures of the cylinder chambers 4, 12 are also fed back tothe feedback pressure spaces 93, 113. That is to say, the sleeves 91,111 move according to the reference pressure and feedback pressure,whereby oil pressures of the pipe lines 6, 13 are changeablycommunicated with the pipe lines 44, 45 resulting in changeablecommunication with high pressure side and low pressure side of the pump15. Accordingly, the oil pressures of the cylinder chambers 4, 12 can becontrolled in accordance with the duty signal from the control unit 200.

The pressure-regulating valve 70 serves as a valve for protection frompressure increase by completely closing the hydraulic circuit. Controlof transmission gear ratio is carried out by complementarily varying(increasing or decreasing) the oil pressures of the cylinder chambers 4,12. More specifically, because length of the belt 14 is fixed, whenincreasing the oil pressure of the cylinder chamber 4 in relation to theoil pressure of the cylinder chamber 12, the pulley 3 moves rightward toincrease the tension diameter of the belt 14 wound round the pulleys 2,3 while decreasing the tension diameter of the belt 14 wound round thepulleys 8, 9, whereby transmission gear ratio is reduced. On the otherhand, the transmission gear ratio is increased when relatively reducingthe oil pressure of the pressure chamber 4. Establishing that arotaional frequency of the input shaft 1 connected to the engine 124through the powder clutch 130 is NE, a rotational frequency of theoutput shaft 7 connected to the vehicle 140 is NO, an equivalent radiusof the input shaft 1 is RE and an equivalent radius of the output shaft7 is RO, the transmission gear ratio can be expressed by ##EQU1## Thetransmission gear ratio is decided in accordance with fuel consumption,driving feeling, driving performance, etc. Accordingly, the control unit200 controls the duty valves 80, 100 by generating a duty signalaccording to engine speed, vehicle speed, throttle opening (drivers'sneed), etc., thereby the transmission gear ratio being controlled. Inaddition, the control unit 200 carries out torque control of the powderclutch 130.

As has been described so far, since control of transmission gear ratiois electrically carried out by the electronic control unit, the controlaccording to the invention is more advantageous than mechanical controlnot only in view of life and secular change but also in view ofperformance such as fuel consumption, driving performance, etc. Cylinderoil pressure of the transmission can be controlled separately dividinginto primary and secondary pressures according to engine controlinformation and driving control information, which also results inimprovement of control accuracy. Furthermore, a compact and small-sizedelectronic control unit is achieved since the hydraulic control means ofoutput oil pressure feedback type is incorporated. The electroniccontrol unit also performs torque control for the powder clutch, wherebycontrol signals of the powder clutch and the non-stage transmission canbe generated from a common input signal, being able to be synchronizedby computer. As the result, time control between the non-stagetransmission and the powder clutch can be easily carried out.

I claim:
 1. A control device of a stepless transmission, comprising:astepless transmission comprising a primary and a secondary pulley havingan endless belt circumscribed therearound, each of said pulleys havingtwo flanges defining a V-shaped groove therebetween and cylinderdisposed adjacent one of said flanges, said one flange being axiallyadjustable by applying hydraulic pressure to said cylinder such that thegroove width and attendantly the effective diameter of each of saidpulleys is variable; an electronic control device which receivesinformation and generates duty control information; a pair of dutyvalves for independently generating respective reference pressures inresponse to the duty control information; a pair of pressure controlvalves comprising a cylindrical sleeve and a spool slidably disposedtherein so as to define a reference pressure space communicating with anassociated duty valve and a feedback pressure space communicating withan associated cylinder, said spaces being disposed on opposite ends ofsaid spool, said spool having a control chamber intermediate of saidreference pressure space and said feedback pressure space, said chambercommunicating with said feedback pressure space and a high pressure linewherein axial movement of said spool causes said high pressure line tocommunicate with said feedback pressure space.
 2. A control device ofnon-stage transmission according to claim 1, wherein said electroniccontrol unit has control means of torque of a powder clutch providedbetween the non-stage transmission and an engine.